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Old adversary

By Tim Thwaites in Sydney

HIV may have been associated with humans for hundreds of years rather than
recently evolving from a chimpanzee virus, says a virologist from New Orleans
after analysing tissue from a young male prostitute who died 30 years ago.

The HIV virus has been found in tissue samples frozen after the teenager died
at St Louis City Hospital in 1969. This pushes back the first recorded case of
AIDS in the US by about a decade: the only earlier known case of human HIV
infection was in Zaire in 1959.

A pathologist preserved the tissue samples after recognising that the boy’s
death from Kaposi’s sarcoma—a cancer that is now widely associated with
AIDS—was unusual.

Robert Garry of Tulane University Medical Center and his colleagues analysed
gene sequences from the blood, spleen, liver and brain. They detected a subtype
of HIV less than one per cent different to HIV-1 sequenced in 1983.

Garry argues that, at that rate of change, it would have taken hundreds of
years for the closest equivalent chimpanzee virus to become HIV. He now believes
the AIDS epidemic may have emerged not because humans acquired HIV from monkeys,
but because existing human strains of HIV mutated to become more infectious.